I actually think the balance is working ok right now. (But we have only 1 child, so same question as CBTECH!) During the workdays, when it's my days to get home, I stay focused on work 8-6. I'm home and playing with DS by 6:45. Bedtime's ~ 8:30. I get all my relaxing in - or evening work like I have to do shortly - until I go to bed. Weekends are nicer of course.
The 'me' time is usually when DS is napping on a weekend, or some weekday evenings. Play time = family time pretty much!